Constrained layer damper

ABSTRACT

A system includes a first layer of a first polymeric material being visco-elastic when solidified. The first polymeric material covers a first portion of a substrate. A second layer of a second polymeric material (being stiff when solidified) covers at least a portion of the first layer and at least a second portion of the substrate. Additionally, a method includes applying a layer of first polymeric material to a first portion of a substrate. The first polymeric material is visco-elastic when solidified. Additionally, a layer of a second polymeric material (being stiff when solidified) is applied to the first polymeric material and a second portion of the substrate. The first polymeric material is constrained between the second polymeric material and the substrate. Both of the first polymeric material and the second polymeric material are dispensed in fluid form from a bulk source of fluid material.

RELATED APPLICATIONS

The present application is a continuation in part of U.S. patentapplication Ser. No. 10/458,889 filed on Jun. 11, 2003, to Robert D.Myers et al., entitled “Constrained Layer Damper,” the contents of whichare included herein by reference in their entirety.

BACKGROUND

The present invention generally relates to constrained layer dampersthat are used to dissipate vibration energy.

Undesirable vibration energy occurs in a variety of products anddevices. For example, in automotive vehicles, the engine and otherautomotive systems can cause vibration energy to permeate through thevehicle body and into the vehicle's passenger compartment. Similarundesirable vibration energy results in a variety of other situations,such as in household appliances and other types of transportationvehicles, to name a few.

To reduce undesirable vibration energy, it is known to adheresingle-layer vibration-damping panels and apply single-layervibration-damping materials to the surfaces of automobile panels,floors, and the like (and to appliances and other devices) to reducevibration effects inside of the passenger compartment. Single-layervibration-damping panels and coatings are relatively cost-effective, andthey do reduce undesirable vibrations. It is also known to useconstrained layer dampers to minimize undesirable vibrations in certaincircumstances. Constrained layer dampers generally consist of a layer ofpolymeric damping material adhered to a surface of a panel of theproduct (e.g., automobile, appliance, etc.) and a stiff outer top layerthat constrains the polymeric damping material, effectively“sandwiching” the polymeric damping material between the stiff outer toplayer and the product panel (the “substrate”). It has been determinedthat constrained layer dampers are generally more effective at reducingundesirable vibration than single layer dampers. However, constrainedlayer dampers are generally more expensive to manufacture and install.

The inventors hereof have recognized the need for an improvedconstrained layer damper and for an improved modular method ofinstalling constrained layer dampers in automated manufacturingsettings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary automated manufacturing setting,including a system for applying a constrained layer damper, showing thefluidic application of a first polymeric material.

FIG. 2 illustrates an exemplary automated manufacturing setting,including a system for applying a constrained layer damper, showing thefluidic application of a second polymeric material.

FIG. 3 is a cross-sectional view of the constrained layer damper,showing a substrate, a first layer of polymeric material, and a secondlayer of polymeric material.

FIG. 4 illustrates an exemplary automated manufacturing setting,including a system for applying a selective constrained layer damper,showing the fluidic application of a first polymeric material.

FIG. 5 illustrates an exemplary automated manufacturing setting,including a system for applying a selective constrained layer damper,showing the fluidic application of a second polymeric material.

FIG. 6 is a perspective view of a completed selective constrained layerdamper, with the constrained layer areas placed a more than one hot spotlocation.

FIG. 7 is a cross-sectional view of the selective constrained layerdamper.

DETAILED DESCRIPTION

An exemplary embodiment of an improved constrained layer damper and amethod of applying a constrained layer damper in an automatedmanufacturing setting is hereinafter disclosed.

The improved constrained layer damper comprises at least two layers ofmaterials. The “base” layer of material is a visco-elastic polymericmaterial, which is applied or adhered directly to a panel (substrate) ofa product for which the vibration-reducing effect is desired. Forexample, in the case of an automotive vehicle, the first layer could beapplied/adhered to a metal floor panel. The first layer of polymericmaterial is chosen so as to adhere well to the substrate in question.This material is designed to maximize damping performance defined by thematerial loss factor in the range of the intended operatingtemperatures. This loss factor is calculated from the phase angle bywhich the stress leads the strain in the deformable solid material. Thisloss factor will be a maximum over the glass transition region of thematerial, and may achieve values in excess of 1.0 in this region. Thecorresponding stiffness of the first layer will be low relative to thestiffness of the top or constraining layer, as described hereinafter.Examples of acceptable materials that can be used as the first layer inthe improved constrained layer damper include, without limitation,acrylic polymers, synthetic resins, emulsions, and bituminous basedmaterials. Examples of suitable materials would include polyurethanes,styrene block co-polymers, polyureas, silane terminated polyurethanes,modified silane polymers, polyisobutylenes, ethylene propylene dienemonomer (EPDM), natural rubber, epoxy resins and other polymer materialsthat can be modified to achieve the desired physical properties. Morespecific, commercially-available, materials that can be employed as thebase layer in the constrained layer damper include: (1) Sikafloor Pronto18, a two component peroxide-cured modified PMMA; (2) SikaTransfloor 352VP, a two component polyurethane; (3) Sikafloor 325, a two componentpolyurethane; (4) PU Read, a two component polyurethane; and (5) FM 100,a styrene butadiene block copolymer, all of which are commerciallyavailable from the assignee hereof.

The improved constrained layer damper further includes an “outer” or“top” layer of material that is applied to the base visco-elasticpolymeric material. The outer layer of material is also a polymericmaterial, but the outer polymeric material layer has a high degree ofstiffness when in its solid state. The stiffness of the outer layer willgenerally be a factor of ten times higher in stiffness than the baselayer, and will have Young's Modulus (E′) in excess of 1.0×(10)⁹ MPaover the glassy region of the material. The outer layer of material isformulated to ensure that the glass transition region of the materialand corresponding roll-off in modulus are above the operatingtemperature range in the application. This material may be homogeneousin nature or may incorporate reinforcing fibers or fillers to enhancestiffness. The outer layer of material may be applied as a single ormultiple component system. Examples of acceptable materials that can beused as the second layer in the improved constrained layer damperinclude, without limitation, epoxy resins, polyureas, acrylic polymers,polyurethanes, epoxy polyurethane hybrids, polyesters, modifiedpolyesters, and other polymers that can be modified to achieve thedesired physical properties. More specific, commercially-available,materials that can be employed as the top layer in the constrained layerdamper include: (1) Sikadur 32, a two component toughened epoxy; (2)Sikafloor 381, a two component chemically-resistant epoxy; and SikaGard62, a two component epoxy.

The respective polymeric materials are chosen so that they adhere wellto each other. Preferably, the respective polymeric materials are chosensuch that they solidify without the application of heat. Specifically,it is preferable that the polymeric materials are chosen such that theysolidify by cooling to room temperature, by drying, by chemical reactionat room temperature, or by other known means of solidifying or curingthat do not require the application of heat above room temperature. Inthis way, the inventive constrained layer damper can be installed ontovehicles (and other manufactured products) in a more flexible way. Thatis, the two layers of the constrained layer damper can be applied afterthe vehicle (or other manufactured product) passes through the paintshop, which is normally the location on the assembly line where hightemperatures are applied to the vehicle. If the constrained layer damperwere to employ materials that required high temperatures to solidify,then the constrained layer damper would have to be applied to thevehicle (or other product) before it reached the paint shop. If thepreferred polymeric materials are used—which do not require heat tosolidify—then the constrained layer damper may be applied after thevehicle passes through the paint shop, which is sometimes desirable tomaintain the integrity of the paint shop process. Furthermore, if thepolymeric materials used for the constrained layer damper do not requireheat to solidify, the different layers can be applied at differentlocations on the assembly line without regard to where the location(s)of application are relative to the paint shop.

In other embodiments of the invention, the improved constrained layerdamper may include more than two layers of material, where the layers ofmaterial alternate between the visco-elastic polymeric material of thefirst layer and the stiff polymeric material of the second outer layer.

The improved constrained layer damper is adapted to be applieddynamically during the manufacture of a product, such as an automotivevehicle, in an automated manufacturing setting. Referring to FIGS. 1 and2, an exemplary automated manufacturing setting is illustrated, which,in this particular example, is a setting for automated manufacturing ofautomotive vehicles. FIGS. 1 and 2 illustrate a partially-manufacturedautomotive vehicle on an assembly line. At the illustrated point in themanufacturing process, the automotive vehicle still has an exposed floorpanel 10 (substrate). It is desirable to include a vibration damper onfloor panel 10 of the automotive vehicle. FIG. 1 illustrates a firstarticulated robot arm 12 a, having an applicator head 14 a with a nozzlefor dispensing fluid materials. The exemplary automated manufacturingsetting also includes a second articulated robot arm 12 b, having anapplicator head 14 b with a nozzle for dispensing fluid material. Thearticulated robot arms 12 a and 12 b are electronically controlled by acontrol device (not shown), such as, for example, a computerworkstation. The articulated robot arms 12 a and 12 b are controlled sothat the robot arms are selectively positioned relative to the floor 10of the automotive vehicle to dispense fluid material thereon.

The first applicator head 14 a disposed on the articulated arm robot 12a is fluidly-connected to at least one source of fluid material (notshown). The second applicator head 14 b disposed on the articulated armrobot 14 b is also fluidly-connected to at least one source of fluidmaterial (not shown), which is different from the fluid source connectedto applicator head 14 a. In some embodiments, the respective sources offluid materials are drums or bulk containers of fluid materials. Variousknown metering and fluid delivery components and systems can be used todeliver desired amounts of the fluid materials from the respectivesources to the corresponding applicator heads on the articulated robotarms.

The above-described system can be used to implement the improvedconstrained layer damper on the floor (or other substrate) of anautomotive vehicle (or other manufactured product). For example, in oneembodiment, a first layer of visco-elastic polymeric material 16 a isdispensed, in fluid form, from the applicator head 14 a of the robot arm12 a onto the substrate 10. The first layer of material is allowed tosolidify and adhere to the substrate 10. Then, as shown in FIG. 2, thesecond layer of material 16 b is dispensed, in fluid form, from theapplicator head 14 b of the robot arm 12 b onto the first layer ofvisco-elastic polymeric material 16 a. The second layer of material 16 bis allowed to solidify into a stiff layer, which “sandwiches” the middlevisco-elastic polymeric material 16 a against the substrate 10, therebycreating the constrained layer damper. FIG. 3 illustrates across-section of the constrained layer damper, wherein a visco-elasticpolymeric material 16 a is “sandwiched” between the substrate 10 of thevehicle and a stiff polymeric material 16 b.

As described above, if polymeric materials that do not require heat tosolidify are chosen for the base and outer layers of the constrainedlayer damper, then the application of the base and outer layers mayoccur anywhere in the assembly/manufacturing process without regard towhere in the process heat may be applied. For example, in the situationof an automotive vehicle, the layers of the constrained layer damper maybe applied subsequent to the paint shop, which, in certain situations,is preferable to maintain the integrity of the paint process.

In another embodiment of the invention, each of the applicator heads 14a and 14 b are configured to dispense a plurality of different versionsof the two different layers of materials that comprise the constrainedlayer damper. For example, a variety of visco-elastic polymericmaterials may be acceptable for use in the disclosed improvedconstrained layer damper, though certain visco-elastic polymericmaterials may have better qualities than others. Many times, thosematerials that have superior qualities are more costly. Therefore, thisembodiment includes a first applicator head 14 a that can dispense, forexample, a plurality of visco-elastic polymeric materials to be used asthe first material layer in the constrained layer damper, applied to thesubstrate 10. Further, applicator head 14 b may be configured todispense one or more different stiff polymeric materials to be used asthe outer layer in the constrained layer damper. In this way, theparticular configuration of the constrained layer damper can becustomized from one automotive vehicle to the next. For example, forVehicle A, a first visco-elastic polymeric material can be dispensedfrom the applicator head onto the substrate and a first stiff polymericmaterial can then be dispensed onto the visco-elastic polymeric materialto form the constrained layer damper. Then, for Vehicle B, which can bethe next vehicle on the same assembly line, second visco-elasticpolymeric material can be dispensed from the applicator head onto thesubstrate of vehicle B. Then, a second stiff polymeric material can bedispensed onto the second visco-elastic polymeric material to form theconstrained layer damper. In this way, it is possible to customize theparticular materials used to form the constrained layer damper from onevehicle to the next. For example, where a relatively inexpensive vehicleand a relatively expensive vehicle are assembled on the same automatedassembly line, higher quality/cost materials can be used to form theconstrained layer damper for the relatively expensive vehicle, and lowerquality/cost materials can be used to form the constrained layer damperfor the relatively inexpensive vehicle. A control device, such as acomputer workstation could be used to control the application of thedifferent materials for different vehicles.

In another embodiment of the invention, the functions of the twoarticulated robot arms 12 a and 12 b could be combined into a singlearticulated robot arm having one or more nozzles configured to dispensea first layer of visco-elastic polymeric material to a substrate 10, aswell as one or more nozzles configured to dispense a second layer ofstiff polymeric material onto the visco-elastic polymeric material. Asin previous embodiments, the articulated robot arm, including thevarious dispensing nozzles thereon, would be electronically controlledby a controller device, such as a computer workstation.

In yet another embodiment, either the visco-elastic polymeric materialor the stiff polymeric material can be applied in a solid piece form,and the other material can be dispensed from an articulated robot arm influid form. For example, a solid piece of visco-elastic polymericmaterial can be applied directly to the substrate of the automotivevehicle. The solid piece of visco-elastic polymeric material can beadhered to the substrate in a variety of known ways, such as by usingheat, ultraviolet radiation, etc. Then, after the solid piece ofvisco-elastic polymeric material is adhered to the substrate, the outerlayer of stiff polymeric material can be dispensed, in fluid form, froman applicator head on a robot arm over the visco-elastic polymericmaterial. The outer polymeric material is solidified, at which time itbecomes stiff and, in combination with the substrate, “sandwiches” themiddle visco-elastic polymeric material. As indicated above, additionalalternating layers of the two polymeric materials can be added to theconstrained layer damper. Alternatively, the first visco-elasticpolymeric material can be dispensed onto the substrate of the automotivevehicle from the applicator head on the articulated robot arm, and thesecond stiff polymeric material can be applied over the visco-elasticpolymeric material in a solid piece. More specifically, the first layerof visco-elastic polymeric material can be dispensed, in fluid form,from the applicator head of the robot arm to the substrate. The fluidmaterial is solidified and adhered to the substrate. Then, a solid pieceof stiff polymeric material can be adhered to the first layer ofvisco-elastic polymeric material. This solid piece of stiff polymericmaterial may be a dedicated constraining layer for the damping system,or this functionality may be incorporated into carpet backing,headliners, or other interior trim components added at a later stage inthe assembly process. Similarly to above, additional alternating layersof the respective materials can be applied to create a multi-layerconstrained layer damper.

In addition to the benefits described above, the application of theimproved constrained layer damper in the manner described allows theconstrained layer damper to be customized even further, depending on theparticular vehicle (or product) upon which it is applied. For instance,the number of alternating layers can be customized, and the thickness ofthe visco-elastic polymeric material and the stiff polymeric materialcan be customized. Moreover, it is possible to apply single-layerdampers to some vehicles on the assembly line and to apply constrainedlayer dampers on other vehicles on the same assembly line.

In another embodiment, an improved damping system having a selectiveconstrained layer damper includes an outer layer over the substrate anda constrained layer placed between the outer layer and the substrate atselected predetermined locations. With a thin additional layer atselective locations the damping system achieves superior dampingproperties at the selective locations. Stated another way, the improveddamping system includes a single layer damper and a two layerconstrained damper at certain locations considered “hot spots.” By usinga single layer system for the overall damper and a constrained dampersystem at areas identified as hot spots, the cost of manufacture, timeof manufacture, weight, overall thickness of the damping system, as wellas other factors, are improved.

A hot spot is an area where it is desirable to have additional damping.That is to say, it is desirable to have more damping than the singlelayer can provide. The hot spot is generally an arbitrary locationidentified on the substrate by a customer, supplier, etc. The additionaldamping at the hot spot reduces vibration or noise when the substrate(or the associated article of manufacture using the substrate) is inuse.

As described below, a constrained layer damper is selectively placed atlocations where additional damping is desired as a treatment to reducestructure-borne sound and/or vibration. Generally, the selectiveconstrained layer damper converts Kinetic energy of a vibrating surfaceinto thermal energy in a polymeric layer, thereby dissipating thevibrational energy. At locations other than the hot spots, anextensional single layer of material is applied to the substrate. Inthis way, the outer layer of the constrained layer damper behaves as asingle dissipative layer for the areas not considered hot spots. Thesingle layer damper converts vibrational energy to heat throughextension and compression of the dissipative layer.

The constrained layer, placed at the identified hot spots, is avisco-elastic polymeric material which is applied or adhered directly toa panel (substrate) of a product for which the vibration-reducing effectis desired. This is similar to the base layer described above. Theconstrained layer portions are not placed as a full layer on thesubstrate, but rather are concentrated at the hot spots. For example, inthe case of an automotive vehicle, the selective constrained layerdamper could be applied/adhered to a metal floor panel. The constrainedlayer of polymeric material is chosen so as to adhere well to thesubstrate in question. This material is designed to maximize dampingperformance defined by the material loss factor in the range of theintended operating temperatures. This loss factor is calculated from thephase angle by which the stress leads the strain in the deformable solidmaterial. This loss factor will be a maximum over the glass transitionregion of the material.

The corresponding stiffness of the constrained layer will be lowrelative to the stiffness of the outer or constraining layer, asdescribed hereinafter. Examples of acceptable materials that can be usedas the constrained layer in the selective constrained layer damperinclude, without limitation, synthetic resin, natural resins, waterbased or solvent type, bituminous or cement based materials, and otherpolymer materials that can be modified to achieve the desired physicalproperties. Other examples include, but are not limited to,polyurethanes, styrene block co-polymers, acrylic polymers, polyureas,silane terminated polyurethanes, modified silane polymers,polyisobutylenes, EPDM, natural rubber, Poly vinyl chloride, epoxyresins, waterbased resins, and bituminous based materials, and othermaterials having visco-elastic properties. Other examples of resinsinclude, but are not limited to, Acrylics,Acrylonitrile-Butadiene-Styrene (ABS), Epoxies, Fluoropolymers,Polyamide-Imides, Polyethylene, Polyimides, Polypropylene, Polystyrene,Polyvinyl Acetate, and Polyesters.

Specific commercially-available materials that can be employed as thebase layer in the selective constrained layer damper include, but arenot limited to: (1) Sikafloor Pronto 18, a two component peroxide-curedmodified PMMA; (2) SikaTransfloor 352 VP, a two component polyurethane;(3) Sikafloor 325, a two component polyurethane; (4) PU Read, a twocomponent polyurethane; and (5) FM 100, a styrene butadiene blockcopolymer, (6) Sikamelt 9283, a thermal plastic rubber based hotmeltadhesive. All of which are commercially available from the assigneehereof.

The selective constrained layer damper further includes an “outer” or“top” layer of material that is applied to the base visco-elasticpolymeric material. The outer layer of material is also a polymericmaterial, but the outer polymeric material layer has a high degree ofstiffness when in its solid state. The stiffness of the outer layer willgenerally be a factor of ten times higher in stiffness than theconstrained layer, and will have Young's Modulus (E′) in excess of1.0×(10)⁹ MPa over the glassy region of the material. The outer layer ofmaterial is formulated to ensure that the glass transition region of thematerial and corresponding roll-off in modulus are above the operatingtemperature range in the application. This material may be homogeneousin nature or may incorporate reinforcing fibers or fillers to enhancestiffness.

The outer layer of material may be applied as a single or multiplecomponent system. Examples of acceptable materials that can be used asthe outer layer in the selective constrained layer damper include,without limitation, synthetic or natural resins, water based or solventtype, bituminous or cement based materials, and other polymer materialsmodified to achieve the desired physical properties. Examples ofsuitable materials would include, but are not limited to, epoxy resins,polyureas, acrylic polymers, polyurethanes, epoxy polyurethane hybrids,polyesters, modified polyesters, waterbased resins, and other polymersthat can be modified to achieve the desired physical properties.Specific commercially-available materials that can be employed as theouter layer in the selective constrained layer damper include, but arenot limited to: (1) Sikadur 32, a two component toughened epoxy; (2)Sikafloor 381, a two component chemically-resistant epoxy; (3) SikaGard62, a two component epoxy; and (4) Sika Damp 1202, a waterbased spray-ondamper material.

The respective polymeric materials that comprise the outer layer andconstrained layer are chosen so that they adhere well to each other.Moreover, because the selective constrained layer damper also includesouter layer 30 as adhering to substrate 10, the material for outer layer30 is chosen for adherence to the constrained layer (e.g., at hot spots20, 22, 24) as well as adherence to the material substrate 10.Additionally, the material chosen for outer layer 30 also takes intoaccount the constraining function, at hot spots 20, 22, 24, as well asthe single layer damping elsewhere.

The respective polymeric materials, in an embodiment, are chosen suchthat they solidify without the application of heat. In this case, thepolymeric materials are chosen such that they solidify by cooling toroom temperature, by drying, by chemical reaction at room temperature,or by other known means of solidifying or curing that do not require theapplication of heat above room temperature. In this way, the selectiveconstrained layer damper can be installed onto vehicles (and othermanufactured products) in a more flexible way. That is, the two layersof the selective constrained layer damper can be applied after thevehicle (or other manufactured product) passes through the paint shop,which is normally the location on the assembly line where hightemperatures are applied to the vehicle. Where polymeric materials areused which do not require heat to solidify, the selective constrainedlayer damper may be applied after the vehicle passes through the paintshop, which is sometimes desirable to maintain the integrity of thepaint shop process. Furthermore, where polymeric materials used for theselective constrained layer damper do not require heat to solidify, thedifferent layers can be applied at different locations on the assemblyline without regard to where the location(s) of application are relativeto the paint shop.

In an alternative embodiment, one or more of the layers (e.g., outerlayer 30 and/or the constrained layer(s) at hot spots 20, 22, 24) may bedried by the application of heat (e.g., in an oven or by direct forcedhot air). That is to say, the outer layer 30 may be air-dried while theconstrained layers may be heat dried. Alternatively, the constrainedlayers may be air-dried while the outer layer is heat dried. Also, theconstrained layers and the outer layer may both be heat dried. By addingthe flexibility to the drying process, outer layer 30 or the constrainedlayer at hot spots 20, 22, 24 may be applied before or after the vehiclepasses through the paint shop.

In other embodiments, the selective constrained layer damper may includemore than two layers of material, where the layers of material alternatebetween the visco-elastic polymeric material of the constrained layerand the stiff polymeric material of the outer layer.

The selective constrained layer damper is adapted to be applieddynamically during the manufacture of a product, such as an automotivevehicle, in an automated manufacturing setting. Referring to FIGS. 4 and5, an exemplary automated manufacturing setting is illustrated, which inthis particular example is a setting for automated manufacturing ofautomotive vehicles. FIGS. 4 and 5 (similar to FIGS. 1 and 2) illustratea partially-manufactured automotive vehicle on an assembly line. At theillustrated point in the manufacturing process, the automotive vehiclestill has an exposed floor panel 10 (substrate). It is desirable toinclude a vibration damper on floor panel 10 of the automotive vehicle.FIG. 4 illustrates first articulated robot arm 12 a, having applicatorhead 14 a with a nozzle for dispensing fluid materials. The exemplaryautomated manufacturing setting also includes second articulated robotarm 12 b, having applicator head 14 b with a nozzle for dispensing fluidmaterial. The articulated robot arms 12 a and 12 b are electronicallycontrolled by a control device (not shown), such as, for example, acomputer workstation. The articulated robot arms 12 a and 12 b arecontrolled so that the robot arms are selectively positioned relative tothe floor 10 of the automotive vehicle to dispense fluid materialthereon.

The first applicator head 14 a disposed on the articulated arm robot 12a is fluidly-connected to at least one source of fluid material (notshown). The second applicator head 14 b disposed on the articulated armrobot 14 b is also fluidly-connected to at least one source of fluidmaterial (not shown), which is different from the fluid source connectedto applicator head 14 a. In some embodiments, the respective sources offluid materials are drums or bulk containers of fluid materials. Variousknown metering and fluid delivery components and systems can be used todeliver desired amounts of the fluid materials from the respectivesources to the corresponding applicator heads on the articulated robotarms.

The above-described system can be used to implement the selectiveconstrained layer damper on the floor (or other substrate) of anautomotive vehicle (or other manufactured product). For example, in oneembodiment, areas of visco-elastic polymeric material 16 a aredispensed, in fluid form, from the applicator head 14 a of the robot arm12 a onto the substrate 10 in selective areas. In the embodiment shown,for example, visco-elastic polymeric material 16 a is dispensed at afirst hot spot 20, a second hot spot 22, and a third hot spot 24. Thehot spots 20, 22, 24 are areas that are desired to have the constrainedlayer damper. The other areas of substrate 10 are not desired to have aconstrained layer damper and thus, will be coated with a single layerdamper as described in FIG. 5.

The first layer of material deposited at hot spots 20, 22, 24 is allowedto solidify and adhere to the hot spots identified on substrate 10.Then, as shown in FIG. 5, an outer layer 30 of material 16 b isdispensed, in fluid form, from the applicator head 14 b of the robot arm12 b onto the constrained layer of visco-elastic polymeric material 16a. Outer layer 30 of material 16 b is allowed to solidify into a stifflayer, which “sandwiches” the middle visco-elastic polymeric material 16a against the substrate 10, thereby creating the selective constrainedlayer damper at each hot spot. Moreover, outer layer 30 is applieddirectly to substrate 10 at locations other than hot spots 20, 22, 24and becomes a single layer damper.

FIG. 6 is a perspective view of a completed selective constrained layerdamper, with the constrained layer placed at more than one location.Shown in phantom lines, hot spots 20, 22, 24 are constrained layerdampers at the hot spots and outer layer 30 is a single layer damperelsewhere. As shown, outer layer 30 substantially covers the entirety ofsubstrate 10. However, it is also foreseen that outer layer 30 willcover only portions of substrate 10. Such a selective application allowsfor attachment points for other assemblies to have direct contact withsubstrate 10. Alternatively, outer layer 30 may only be desired to beapplied to portions of substrate 10 that realize vibration. Otherportions of substrate 10 may not require damping and thus, would not becovered by outer layer 30.

FIG. 7 illustrates a cross-section of the selective constrained layerdamper at hot spot 22, wherein a visco-elastic polymeric material 16 ais “sandwiched” between the substrate 10 of the vehicle and a stiffpolymeric material 16 b. The single layer portion of the selectiveconstrained layer damper comprises outer layer 30 that adheres tosubstrate 10 at interface 40. A portion of hot spot 22 is shown thatforms a constrained layer damper comprising the constrained layer 22that adheres to outer layer 30 at interface 42 and also adheres tosubstrate 10 at interface 44. In the embodiment shown, the constrainedlayer (e.g., hot spot layers 20, 22, 24) comprises a layer ofvisco-elastic material that is approximately zero point four millimeters(0.4 mm) thick. Outer layer 30 is approximately three millimeters (3 mm)thick, and the substrate (as a metal) is zero point eight millimeters(0.8 mm) thick.

If polymeric materials that do not require heat to solidify are chosenfor the constrained layer and outer layer of the selective constrainedlayer damper, then the application of the constrained layer and outerlayer may occur anywhere in the assembly/manufacturing process withoutregard to where in the process heat may be applied. For example, in thesituation of an automotive vehicle, the layers of the selectiveconstrained layer damper may be applied subsequent to the paint shop,which, in certain situations, is preferable to maintain the integrity ofthe paint process.

As discussed above, alternative embodiments provide that outer layer 30and/or the constrained layer at hot spots 20, 22, 24 are dried by theapplication of heat (e.g., in an oven or by direct forced hot air). Inthis way outer layer 30 may be air-dried while the constrained layersmay be heat dried. Alternatively, the constrained layers may beair-dried while the outer layer is heat dried. Also, the constrainedlayers and the outer layer may both be heat dried. Therefore, outerlayer 30 or the constrained layer at hot spots 20, 22, 24 may be appliedbefore or after the vehicle passes through the paint shop.

In another embodiment, each of the applicator heads 14 a and 14 b areconfigured to dispense a plurality of different versions of the twodifferent layers of materials that comprise the selective constrainedlayer damper. For example, a variety of visco-elastic polymericmaterials may be acceptable for use in the disclosed selectiveconstrained layer damper, though certain visco-elastic polymericmaterials may have better qualities than others. Many times, thosematerials that have superior qualities are more costly. Therefore, thisembodiment includes a first applicator head 14 a that can dispense, forexample, a plurality of visco-elastic polymeric materials to be used asthe first material layer in the selective constrained layer damper,applied to the substrate 10. Further, applicator head 14 b may beconfigured to dispense one or more different stiff polymeric materialsto be used as the outer layer in the selective constrained layer damper.In this way, the particular configuration of the selective constrainedlayer damper can be customized from one automotive vehicle to the next.

For example, for Vehicle A, a first visco-elastic polymeric material canbe dispensed from the applicator head onto the substrate and a firststiff polymeric material can then be dispensed onto the visco-elasticpolymeric material to form the selective constrained layer damper. Then,for Vehicle B, which can be the next vehicle on the same assembly line,second visco-elastic polymeric material can be dispensed from theapplicator head onto the substrate of vehicle B. Then, a second stiffpolymeric material can be dispensed onto the second visco-elasticpolymeric material to form the selective constrained layer damper. Inthis way, it is possible to customize the particular materials used toform the selective constrained layer damper from one vehicle to thenext. For example, where a relatively inexpensive vehicle and arelatively expensive vehicle are assembled on the same automatedassembly line, higher quality/cost materials can be used to form theselective constrained layer damper for the relatively expensive vehicle,and lower quality/cost materials can be used to form the selectiveconstrained layer damper for the relatively inexpensive vehicle. Acontrol device, such as a computer workstation could be used to controlthe application of the different materials for different vehicles.

In another embodiment, the functions of the two articulated robot arms12 a and 12 b could be combined into a single articulated robot armhaving one or more nozzles configured to dispense a first layer ofvisco-elastic polymeric material to a substrate 10, as well as one ormore nozzles configured to dispense a second layer of stiff polymericmaterial onto the visco-elastic polymeric material. As in previousembodiments, the articulated robot arm, including the various dispensingnozzles thereon, would be electronically controlled by a controllerdevice, such as a computer workstation.

In yet another embodiment, either the visco-elastic polymeric material(e.g., the constrained layer for the hot spots) or the stiff polymericmaterial (the outer layer) can be applied in a solid piece form, and theother material can be dispensed from an articulated robot arm in fluidform. For example, a solid piece or pieces of visco-elastic polymericmaterial can be applied directly to the substrate of the automotivevehicle at locations identified as hot spots. The solid piece(s) ofvisco-elastic polymeric material can be adhered to the substrate in avariety of known ways, such as by using heat, ultraviolet radiation,etc. Then, after the solid piece of visco-elastic polymeric material isadhered to the substrate, the outer layer of stiff polymeric materialcan be dispensed, in fluid form, from an applicator head on a robot armover the visco-elastic polymeric material. The outer polymeric materialis solidified, at which time it becomes stiff and, in combination withthe substrate, “sandwiches” the middle visco-elastic polymeric materialto form a constrained layer damping system at the hot spots, as well asproviding a single layer damper where the outer layer directly adheresto substrate 10.

As indicated above, additional alternating layers of the two polymericmaterials can be added to the selective constrained layer damper.Alternatively, the first visco-elastic polymeric material can bedispensed onto the substrate of the automotive vehicle from theapplicator head on the articulated robot arm, and the second stiffpolymeric material can be applied over the visco-elastic polymericmaterial in a solid piece. More specifically, the first layer ofvisco-elastic polymeric material can be dispensed, in fluid form, fromthe applicator head of the robot arm to the substrate. The fluidmaterial is solidified and adhered to the substrate. Then, a solid pieceof stiff polymeric material can be adhered to the first layer ofvisco-elastic polymeric material. This solid piece of stiff polymericmaterial may be a dedicated constraining layer for the damping system,or this functionality may be incorporated into carpet backing,headliners, or other interior trim components added at a later stage inthe assembly process. Similarly to the examples above, additionalalternating layers of the respective materials can be applied to createa multi-layer selective constrained layer damper.

In addition to the benefits described above, the application of theselective constrained layer damper in the manner described allows theselective constrained layer damper to be customized even further,depending on the particular vehicle (or product) upon which it isapplied. For instance, the number of alternating layers can becustomized and the thickness of the visco-elastic polymeric material andthe stiff polymeric material can be customized. Moreover, it is possibleto apply single-layer dampers to some vehicles on the assembly line andto apply selective constrained layer dampers on other vehicles on thesame assembly line. Additionally, the placement of the constrained layerdampers at hot spots 20, 22, 24 may change with each vehicle, or may notbe desired for some vehicles. In this way, the customized applicationmethods may apply full constrained layer dampers, selective constrainedlayer dampers, or single layer dampers, and may switch therebetween,depending upon the vehicle under assembly.

Preferred embodiments have been disclosed. A person of ordinary skill inthe art would realize, however, that certain modifications would comewithin the teachings of this Invention, and the following claims shouldbe studied to determine the true scope and content of the invention. Inaddition, the methods and structures of representative embodiments canbe incorporated in the form of a variety of embodiments, only a few ofwhich are described herein. It will be apparent to the artisan thatother embodiments exist that does not depart from the spirit of theinvention. Thus, the described embodiments are illustrative and shouldnot be construed as restrictive.

1. A system comprising: a first layer of a first polymeric materialbeing visco-elastic when solidified, said first polymeric materialcovering a first portion of a substrate; and a second layer of a secondpolymeric material covering at least a portion of said first layer andcovering at least a second portion of said substrate, said secondpolymeric material being stiff when solidified.
 2. The system of claim1, wherein at least one of said first and said second polymericmaterials dispensed in fluid form solidifies at room temperature withoutthe addition of an external, non-chemical catalyst.
 3. The system ofclaim 1, wherein at least one of said first and said second polymericmaterials dispensed in fluid form solidifies when heated above roomtemperature.
 4. The system of claim 1, wherein at least one of saidfirst polymeric material and said second polymeric material is dispensedfrom an applicator head disposed on an articulated robot arm.
 5. Thesystem of claim 1, wherein said first polymeric material and said secondpolymeric material are dispensed from separate sources of fluidmaterial.
 6. The system of claim 5, wherein said first polymericmaterial and said second polymeric material are both dispensed from acommon applicator head disposed on an articulated robot arm.
 7. Thesystem of claim 5, wherein a first version of said first polymericmaterial is applied to a first product and a second version of saidfirst polymeric material is applied to a second product, and said firstversion and said second version have relatively different vibrationdamping characteristics.
 8. The system of claim 5, wherein saidsubstrate is a panel of an automotive vehicle.
 9. The system of claim 1,wherein a first version of said first polymeric material is applied to afirst product and a second version of said first polymeric material isapplied to a second product, and said first version and said secondversion have relatively different vibration damping characteristics. 10.The system of claim 1, wherein said first polymeric material is a firstthickness and said second polymeric material is a second thickness whensaid substrate forms part of a first product of manufacture; and saidfirst polymeric material is a third thickness and said second polymericmaterial is a fourth thickness when said substrate forms part of asecond product of manufacture.
 11. The system of claim 1, wherein saidsubstrate is a panel of an automotive vehicle.
 12. The system of claim1, wherein said first polymeric material is selected from the groupconsisting of synthetic water based resins, synthetic solvent basedresins, natural water based resins, natural solvent based resins,bituminous based materials, cement based materials, polyurethanes,styrene block co-polymers, acrylic polymers, polyureas, silaneterminated polyurethanes, modified silane polymers, polyisobutylenes,EPDM, natural rubber, Poly vinyl chloride, epoxy resins, and waterbasedresins.
 13. The system of claim 1, wherein said second polymericmaterial is selected from the group consisting of epoxy resins,polyureas, acrylic polymers, polyurethanes, epoxy polyurethane hybrids,polyesters, modified polyesters, and waterbased resins.
 14. A methodcomprising: Applying a layer of first polymeric material to a firstportion of a substrate, said first polymeric material beingvisco-elastic when solidified; applying a layer of second polymericmaterial to said first polymeric material and a second portion of saidsubstrate such that said first polymeric material is constrained betweensaid second polymeric material and said substrate, said second polymericmaterial being stiff when solidified; and wherein both said firstpolymeric material and said second polymeric material are dispensed influid form from a bulk source of fluid material.
 15. The method of claim14, wherein at least one of said first and said second polymericmaterials dispensed in fluid form solidifies at room temperature withoutthe addition of an external, non-chemical catalyst.
 16. The method ofclaim 14, wherein at least one of said first and said second polymericmaterials dispensed in fluid form solidifies when heated above roomtemperature.
 17. The method of claim 14, wherein at least one of saidfirst polymeric material and said second polymeric material is dispensedfrom an applicator head disposed on an articulated robot arm.
 18. Themethod of claim 14, wherein said first polymeric material and saidsecond polymeric material are dispensed from separate sources of fluidmaterial.
 19. The method of claim 18, wherein said first polymericmaterial is dispensed from a first applicator head disposed on a firstarticulated robot arm; and said second polymeric material is dispensedfrom a second applicator head disposed on a second articulated robotarm.
 20. The method of claim 18, wherein said first polymeric materialand said second polymeric material are both dispensed from a commonapplicator head disposed on an articulated robot arm.
 21. The method ofclaim 18, wherein said applying a layer of first polymeric material tosaid substrate comprises applying a first version of said firstpolymeric material to a first product and applying a second version ofsaid first polymeric material to a second product, and said firstversion and said second version of said first polymeric material haverelatively different vibration damping characteristics.
 22. The methodof claim 18, wherein said substrate is a panel member of an automotivevehicle.
 23. The method of claim 14, wherein said applying a layer offirst polymeric material to said substrate comprises applying a firstversion of said first polymeric material to a first product and applyinga second version of said first polymeric material to a second product,and said first version and said second version of said first polymericmaterial have relatively different vibration damping characteristics.24. The method of claim 14, further comprising: applying a firstthickness of at least one selected from said fluidic first polymericmaterial and said fluidic second polymeric material when said substrateforms part of a first product of manufacture; and applying a secondthickness of the at least one selected from said fluidic first polymericmaterial and said fluidic second polymeric material when said substrateforms part of a second product of manufacture.
 25. The method of claim14, wherein said substrate is a panel member of an automotive vehicle.26. The method of claim 14, wherein said first layer material isselected from the group consisting of synthetic water based resins,synthetic solvent based resins, natural water based resins, naturalsolvent based resins, bituminous based materials, cement basedmaterials, polyurethanes, styrene block co-polymers, acrylic polymers,polyureas, silane terminated polyurethanes, modified silane polymers,polyisobutylenes, EPDM, natural rubber, Poly vinyl chloride, epoxyresins, and waterbased resins.
 27. The method of claim 14, wherein saidsecond layer material is selected from the group consisting of epoxyresins, polyureas, acrylic polymers, polyurethanes, epoxy polyurethanehybrids, polyesters, modified polyesters, and waterbased resins.
 28. Amethod for installing a constrained layer damper on a product ofmanufacture, comprising: applying a first layer of a first polymericmaterial to a first portion of a substrate of the product, said firstpolymeric material being visco-elastic; applying a second layer of asecond polymeric material to at least a portion of said first polymericmaterial and a second portion of said substrate, such that said firstpolymeric material is constrained between said second polymeric materialand the substrate of the product, said second polymeric material beingstiff when solidified; and wherein at least one of said first polymericmaterial and said second polymeric material is dispensed in fluid formduring the manufacture of the product from a bulk source of fluidmaterial.
 29. The method of claim 28, wherein at least one of said firstand second polymeric materials solidify without the application of heatabove room temperature, and the first polymeric material is selectedfrom the group consisting of a bituminous based material, a silaneterminated polyurethane, a polyurea, and an epoxy polyurethane hybrid.30. The method of claim 28, wherein at least one of said first andsecond polymeric materials solidify when heated above room temperature.31. The method of claim 28, wherein the first polymeric material isselected from the group consisting of synthetic water based resins,synthetic solvent based resins, natural water based resins, naturalsolvent based resins, bituminous based materials, cement basedmaterials, polyurethanes, styrene block co-polymers, acrylic polymers,polyureas, silane terminated polyurethanes, modified silane polymers,polyisobutylenes, EPDM, natural rubber, Poly vinyl chloride, epoxyresins, and waterbased resins.
 32. The method of claim 28, wherein saidsecond polymeric material is selected from the group consisting of epoxyresins, polyureas, acrylic polymers, polyurethanes, epoxy polyurethanehybrids, polyesters, modified polyesters, and waterbased resins.